locking/barriers, kcsan: Support generic instrumentation

Thus far only smp_*() barriers had been defined by asm-generic/barrier.h
based on __smp_*() barriers, because the !SMP case is usually generic.

With the introduction of instrumentation, it also makes sense to have
asm-generic/barrier.h assist in the definition of instrumented versions
of mb(), rmb(), wmb(), dma_rmb(), and dma_wmb().

Because there is no requirement to distinguish the !SMP case, the
definition can be simpler: we can avoid also providing fallbacks for the
__ prefixed cases, and only check if `defined(__<barrier>)`, to finally
define the KCSAN-instrumented versions.

This also allows for the compiler to complain if an architecture
accidentally defines both the normal and __ prefixed variant.

Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

diff --git a/include/asm-generic/barrier.h b/include/asm-generic/barrier.h
index 27a9c9e..02c4339 100644 (file)
--- a/include/asm-generic/barrier.h
+++ b/include/asm-generic/barrier.h
@@ -22,6 +22,31 @@
 #endif
 
 /*
+ * Architectures that want generic instrumentation can define __ prefixed
+ * variants of all barriers.
+ */
+
+#ifdef __mb
+#define mb()   do { kcsan_mb(); __mb(); } while (0)
+#endif
+
+#ifdef __rmb
+#define rmb()  do { kcsan_rmb(); __rmb(); } while (0)
+#endif
+
+#ifdef __wmb
+#define wmb()  do { kcsan_wmb(); __wmb(); } while (0)
+#endif
+
+#ifdef __dma_rmb
+#define dma_rmb()      do { kcsan_rmb(); __dma_rmb(); } while (0)
+#endif
+
+#ifdef __dma_wmb
+#define dma_wmb()      do { kcsan_wmb(); __dma_wmb(); } while (0)
+#endif
+
+/*
  * Force strict CPU ordering. And yes, this is required on UP too when we're
  * talking to devices.
  *